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Full text of "Pest management approach in Quebec apple orchards."

■ j|^ Agriculture 



Canada 

Research Direction generale 
Branch de la recherche 



Contribution 1983-15E 




Pest management approach 
in Quebec apple orchards 







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Pest management approach 
in Quebec apple orchards 



RODOLPHE OMER PARADIS 

Research Station 

Saint- Jean-sur-Richelieu, Quebec 

Technical Bulletin No. 16 revised 



Research Branch 
Agriculture Canada 
1983 



Copies of this publication are available from 

Research Station 

Research Branch 

Agriculture Canada 

P.O. Box 457 

Saint-Jean-sur-Richelieu, Quebec 

J3B 6Z8 

Produced by Research Program Service 

©Minister of Supply and Services Canada 1983 

Egalement disponible en francais sous le titre 
Lutte rationnelle contre les ravageurs 
des pommes au Quebec 



Resume 



Les insectes et les acariens ravageurs presents dans les porameraies du 
sud-ouest du Quebec sont passes en revue en fonction de leur comportement 
relie au developpement phenologique du cultivar Mcintosh ainsi qu'a des 
constantes thermiques. II est fait mention egalement des principaux 
ennemis naturels de ces ravageurs. 

La lutte chimique preconisee comporte cinq traiteraents appliques a des 
stades-reperes et a des dates predetermines; ces traitements sont diriges 
contre les ravageurs preponderants qui sont le Tetranyque rouge du 
pommier, Panonychus ulmi (Koch), la Mouche de la pomme, Ehagoletis 
pomonella (Walsh), les Punaises Lygus lineolavis (P. de B.)> Lygoaoris 
communis (Knight) et Lygidea mendax Reut., la Noctuelle du fruit vert, 
Orthosia hibisci (Guenee) , et le Charancon de la prune, Conotrachelus 
nenuphar (Hbst.)- Des essais de piegeage sont en cours et visent 
essentiellement a reduire le nombre de traitements insecticides. 



Note Contribution n° J. 847 de la Station de Recherches, Direction 
generale de la Recherche, Agriculture Canada, Saint-Jean-sur- 
Richelieu, Quebec. 

Communication presentee le 20 aout 1980 , au Colloque International 
sur 1 'Horticulture patrone par les Floralies de Montreal, Quebec 



Abstract 

The appearance and behaviour of phytophagous insects and mites occurring 
in apple orchards in southwestern Quebec are presented along with the 
phenological development of the cultivar Mcintosh coupled with degree-day 
summations. Natural enemies of these pests are also mentioned. 

Chemical control measures require five pesticide treatments applied at 
different apple bud development stages and pre-determined dates. These 
treatments are directed against the major pests, viz. the European red 
mite, Panonychus ulmi (Koch), the apple maggot, Ehagoletis pomonella 
(Walsh), the bugs Lygus lineolaris (P. de B.), Lygocoris communis (Knight) 
and Lygidea mendax Reut., the green fruitworm, Orthosia hibisci (Guenee) , 
and the plum curculio, Conotrachelus nenuphar (Hbst.). Monitoring 
techniques are being evaluated with the aim of reducing pesticide 
treatments in apple orchards. 



Note Contribution No. J. 847, Research Station, Research Branch, 
Agriculture Canada, Saint-Jean-sur-Richelieu, Quebec. 

Paper presented at a colloquium on horticulture held at 

the International Floralies, Montreal, Quebec, August 20, 1980 



First of all, I want to emphasize that this paper has been preparad with 
the assistance of my colleagues in the field of orchard protection in 
Quebec, Mr. Marcel Mailloux of the Quebec Department of Agriculture, 
Fisheries and Food, and Messrs. Irenee Rivard and Noubar Bostanian of 
Agriculture Canada. I have also made use of certain information provided 
by Mr. Guy Boivin, a student at McGill University, who is studying the 
complex of phytophagous plant bugs in apple orchards, and by Mr. Denis 
Bouchard, of the Universite du Quebec a Montreal, whose research deals 
with apple aphids. 

The first part of this paper deals with the entomofauna of the apple 
orchards of southwestern Quebec as it appears over the course of a season, 
first in relation with the phenological development of the cultivar 
Mcintosh, which clearly predominates in our orchards, and then in relation 
to the calendar months for the rest of the season. For each of these 
stages, we give degree-days, calculated above 5° C by the simple method of 
(maximum + minimum/2) - 5° C. These thermal constants have been collected 
over the past ten years. 

The entomofauna includes both pests and some of their principal natural 
enemies. Given the very large number of pests which attack apple trees, 
we have divided them into three categories: major pests, responsible for 
economic losses in most orchards unless treated; secondary pests 3 which 
cause serious local and episodic damage, and occasional pests 3 which in 
most cases cause negligible damage. 

In the second part of the paper, we deal with the program of monitoring 
and control developed in recent years and further attempst to expand an 
improve upon it. 



I - ENTOMOFAUNA OF APPLE ORCHARDS IN RELATION TO PHENOLOGY 

SPRING DORMANCY 



Period concerned: March 


1 - 


April 


28 


Degree-days* as of April 


1: 


9 






as of April 


15: 


20 






Major pests: 










Green fruitworm 










Tarnished plant bug 










Occasional pests: 










Pale apple leafroller 








Natural enemy: 










Allothrombium lerouxii 








* Above 5° C, average of 


past 10 


years 



When the apple trees are still in their period of spring dormancy (PI. I, 
fig. 1), certain insects are already emerging from hibernation and 
beginning their activity. This is true of the green fruitworm, Orthosia 
hibisci (Guenee), and of the tarnished plant bug, Lygus Zineolaris 
(P. de B.), two insects currently classified as major pests in Quebec's 
apple orchards, that is, capable of causing economic losses in a very large 
number of orchards if untreated. 

Green fruituorm 

In 1980, the first catch of green fruitworm moths, by means of pheromone 
traps, occurred on April 10, approximately two weeks before the green-tip 
stage of the buds. The moths of this species are a greyish beige in 
colour, with densely hairy head and thorax and a wingspan of approximately 
40 mm (PI. II, fig. 12). They fly about in orchards normally until mid- 
May. 

Tarnished plant bug 



The first adults of the tarnished plant bug were captured on April 15, 



in 1980. They are small, oval-shaped, dull brown insects, measuring 6 mm 
in length, which fly away rapidly when disturbed (PI. II, fig. 3). 

Pale apple leafvollev 

The ale apple leaf roller , Pseudexentera mali Free., is the only apple leaf 
roller which, according to our observations, attacks only apple trees, 
since other leaf rollers eventually infest various forest species. It owes 
its name to the whitish colour of the larvae, which are found well hidden 
in the leading shoots of the branches. We have occasionally observed 
P. mali adults flying about the orchards on April 8 and 9, when the maximum 
daily temperature was 12° C and the snow on the ground had not completely 
disappeared. 

Alio -thrombium lerouxii Moss (PI. IV, fig. 1) 

Among the rare entomophagous species present in orchards at this time of 
the year, we should mention the mite A. lerouxii, which is 3,3 ram long and 
a velvety red, and is often plentiful immediately following the melting 
of the snow. It can be found hidden in dead leaves on the groung and it 
voraciously attacks the eggs and other forms of various species of mites 
and insects. 

GREEN TIP 

The budding of the apple trees, known in English as 'green tip' and 
frequently translated into French as 'bouton vert' or 'pointe verte', is 
an extremely important stage (PI. I, fig. 2). Besides being the first 
visible sign of renewed growth, it is at this period that apple scab, 
Venturia inaequalis (Cke.) Wint., may infect apple trees and that many 
pests make their presence known. In southwestern Quebec, the earliest 
date for the green tip stage in Mcintosh trees has been noted on April 16 
and the latest on May 13; the average date however is April 29. 



Average date: April 29 

Extreme dates: April 16 and May 13 

Degree-days: 65 

Major pest: 

Tarnished plant bug 
Secondary pests: 

Apple rust mite 

Red-banded leafroller 

Eyespotted bud moth 

Oblique-banded leafroller 
Occasional pests: 

Apple grain aphid 

Tent caterpillar 

Forest tent caterpillar 

Click beetles 
Natural enemies: 

Syrphid flies 

Lady beetles 



Tarnished plant bug 

Here again we find the tarnished plant bug, which feeds by puncturing the 
flower and leaf buds, thus causing them to exsude fluid and dry out. We 
have observed that, in some plantings, the proportion of buds thus 
destroyed can easily be in the range of 30 %. 

Apple rust mite (Pi. II 3 fig. 2) 



The apple rust mite, Aculus sohleohtendali (Nal.)» is an increasingly 
frequent and serious pest in Quebec's apple orchards. Measuring 
approximately 0,07 mm in length, it is invisible to the naked eye, but as 
the season progresses and leaves turn brown, its presence becomes 



readily apparent. The hibernating females, described as deutogynes, leave 
the budscales in which they have passed the winter to attack foliar tissue 
during the green tip stage. 

Red-banded leaf roller 

After spending the winter in pupal form in plant litter on the ground, the 
first moths of the red-banded leaf roller , Argyro taenia Velutinana (Wlk.), 
are caught by means of synthetic pheromones at the green tip stage. These 
are small moths with a wingspan of approximately 13 mm, the forewings 
having an oblique shaded band of red and brown. 

Adults of the hibernating generation continue to be caught until mid-June. 
Sometimes large numbers are captured, but it should be emphasized that the 
species is polyphagous and that the caterpillars may be present in greater 
quantities, for example, on plants of the genus Apocynum sp. growing in 
certain orchards than on the apple trees themselves. 

Oblique -banded leaf roller and Eyespotted bud moth (PI. Ill, figs. 4 and 8) 

The oblique-banded leaf roller , Arahips rosaceana (Harr.), and the apple 
budmoth, Spilonota ocellana (D. & S.), spend the winter as young 
caterpillars on the trees. During the green tip stage these caterpillars 
begin their activities again, hiding inside the buds to feed. 
A. rosaceana caterpillars are yellowish green with darker heads, while 
S. ooellana are chocolate brown. 

Apple grain aphid 

Of the four species of aphids found on apple trees, the apple grain aphid, 
Rhopalosiphum fitchii (Sand.), is the first to make its appearance. 
Populations are rarely large enough to require treatment. At the calyx 
stage, the winged forms appear, and then migrate to various grains and 
grasses . 



Eastern tent caterpillar and Forest tent caterpillar 

At the end of April, at the green tip stage, the caterpillars of Malacosoma 
amerieanum (F.) and Malacosoma disstria Hbn. appear. The caterpillars 
of both species live in colonies, but only those of M. amerieanum spin 
webs in the forks of the trees. In carefully maintained orchards, they 
are readily eliminated by regular applications of insecticide. Their larval 
stage is completeted by mid-June. 

Click beetles 

These are the adults of the wireworras. Some of these adults, particularly 
those of the genus Ctenicera spp., eat the buds of the apple trees and 
attack the blossoms as well, after which they leave the apple trees. They 
are occasional pests. 

Syrphid flies 

At the green tip stage, it is possible to find syrphid eggs laid on buds 
infested by the apple grain aphid (PI. IV, figs. 2 and 3). The larvae of 
these Diptera are among the major predators of aphids throughout the entire 
season. According to studies carried out by Mr. Denis Bouchard, there are 
at least seven species in our orchards. 

Lady beetles (PI. IV, fig. 3a) 

Early in the season, we find large numbers of lady beetles moving about 

in search of food. Eight species which attack aphids have been identified. 

HALF- INCH GREEN 

Advanced budding is characterized by leaves at least 12 mm in length. 
American pomologists use the expression 'half-inch green' to describe 
this stage. In French, it is often known as 'bouton vert avance' or 



8 



'oreilles de souris' (PI. I, fig. 3). Apple trees reach this stage of 
development at an average date of May 2, while the extreme dates are April 
20 and May 20. Degree-days accumulated by this point total approximately 
85 units. At this phenological stage, the first dandelions, Taraxacum 
officinale^ and trilliums, Trillium grandiflorum and T. erectum 3 appear 
in the orchards. 

At the half-inch green stage, we find the pests already listed, plus the 
two-spotted spider mite, Tetranychus urticae Koch, the rosy apple aphid, 

Dysaphis plantaginea (Pass.), the tentiform leafminer, Lithocolletis blancardella 
(F.) and the gypsy moth, Lyman tria dispar (L.). 



Average date: 


May 2 










Extreme dates: 


April 


20 


and 


May 


20 


Degree-days : 


85 










Secondary pests: 










Two-spottec 


spider 


mite 






Rosy apple 


aphid 










Occasional pests: 










Tentiform 1 


eafminer 










Gypsy moth 













Two- spotted spider mite 



The two-spotted spider mite is a cosmopolitan and polyphagous mite found 
in greenhouses as well as in the field; it is classed as a secondary pest 
of Quebec apple orchards. The hibernating females, which are an orangeish 
yellow in colour, normally appear at the half-inch green stage. At this 
point they are found on herbaceous plant growing in the orchards, 
particularly white campion, Lychnis alba. It is not until late June or 
early July, when the cover crops have dried up or been mowed back, that 
the two-spotted spider mite attacks the apple trees. The species 



completes five or six generations in southwestern Quebec. 

Rosy apple aphid (PI. Ill, figs. 2 and 3) 

Heavy infestations of the rosy apple aphid occur only very sporadically. 
In addition, in mid-June, there is a heavy migration of the winged forms 
to secondary hosts. 

Appleminers 

The complex of appleminers in Quebec includes the following species: 
Li-thocolletis malimalifoliella (Braun) , L. scuderella (F. & B.), L. 
crataegella Clem., and L. blanoardella (F.). L. blanoardella is currently 
predominant; it completes three generations annually and spends the 
winter as a pupa in the dead leaves. The adults make their appearance at 
the half-inch green stage. During the spring of 1980, we monitored 
L. blancardella for the first time, by means of a synthetic sexual 
pheromone. 

Gypsy moth 

There has been a renewed outbreak of this pest on deciduous species in 
several regions of Quebec. In some orchards, in recent seasons, we have 
observed the presence of the blackish, long-haired caterpillars of the 
gypsy moth, which often feed on the upper surface of the leaves. Their 
development is completed by the second half of June. However, to date, 
heavy infestations of orchards have occurred only occasionally. 

TIGHT CLUSTER 

At shis stage, flower buds begin to appear, but they are all clustered 
tightly together; hence the English expression 'tight cluster' (PI. I, 
fig. A). The average date for the appearance of the tight cluster is 
May 9, while the extreme dates range from April 29 to May 23. 



10 



Average date: May 9 

Extreme dates: April 29 and May 23 

Degree-days: 125 

Major pest: 

Green fruitworm 
Secondary pest: 

Apple aphid 



Green fruituovm (PI. II, figs. 11 and 13) 

At this point in the season, the caterpillars of the green fruitworm 
appear; they continue to develop until approximately two weeks after 
petal-fall. These caterpillars attack the buds and new shoots and later 
the newly formed apples, in which they leave deep holes and cavities. 
They are pale green, lightly lined in white; at full size, they measure 30 
to 40 mm in length. 

Apple aphid (PI. Ill, fig. 1) 

At the tight cluster stage, we observe colonies of the apple aphid, Aphis 
pomi De G, on the leading shoots. This species spends the entire season 
on the apple tree. The winged forms, which appear somewhat later, enable 
it to spread throughout the orchards. When populations become extremely 
dense during the course of the season, they cause sooty fungus on the 
foliage and fruit. 

PINK BUD 



At this stage, the flower buds become separated from one another and each 
bud shows a distinctly pink section of petals (PI. I, fig. 5). The pink 
bud stage normally occurs in mid-May; however, the earliest date has been 
May 6, and the latest, May 29. At this stage, there has been a total of 
165 degree-days. 



11 



Average date: May 15 
Extreme dates: May 6 and 29 
Degree-days: 165 
Major pests: 

European red mite 

Plum curculio 
Secondary pest: 

Fruit-tree leafroller 



European red mite (PI. II, fig. 1) 

The eggs of the European red mite, Panonychus ulmi (Koch), which have 
spent the winter on the bark of the branches and trunks, hatch in large 
numbers each year at the pink bud stage. It should be noted that P. ulmi 
is one of the worst apple pests in Quebec. It multiplies very readily 
on the trees, and can complete six or seven generations in a season. In 
order to feed, it sucks out the cullular material from the leaves, leaving 
them discoloured; it thus reduces the vigour of the tree and the development 
of the fruit buds; it can even cause premature dropping of the fruit. 
The cost of treatments applied against the European red mite and other 
mites represents approximately 30 % of the total cost of treatments against 
all pests. 

Plum curculio (PI. II, fig. 8) 



The first hibernating adults of the plum curculio, Cono trachelus nenuphar 
(Hbst.), also appear at the pink bud stage. Despite its name, this 
insect if found predominantly in Quebec's apple orchards and, because it 
has very few natural enemies, insecticides must be used to protect the 
apples from its attacks. 



12 



Fruit-tree leafroller (PI. Ill, fig. 9) 

The fruit-tree leafroller , Archips argyrospilus (Wlk.), is classified as 
a secondary pest. The eggs, laid in patches on the bark of the trees, 
constitute the hibernation stage and hatch primarily during the pink bud 
stage. The caterpillars, which are green with black heads, eat the first 
elements of the foliar tissues and the various floral organs; then, using 
strands of silk, they roll the leaves into sheaths in which they hide, 
eating the foliar parenchyma here and there and also attacking newly 
formed apples in the vicinity of their shelter. The damage caused to the 
fruit can be easily confused with that caused at the same period by the 
caterpillars of the green fruitworm and those of the oblique-banded leaf 
roller (PI. II, fig. 13, PI. Ill, fig. 10). 

FULL PINK 



Average date: May 19 

Extreme dates: May 9 and May 31 

Degree-days: 200 

Secondary pests: 

Apple redbug 

Green apple bug 
Occasional pest: 

Pear thrips 



This stage is fairly closely related to the preceding one. It is 
distinguished by the fact that the petals are much more highly developed 
but are still clustered together, forming a pink and white balloon 
(PI. I, fig. 6). The average date of appearance of the full pink bud 
stage is May 19, with an accumulated total of 200 degree-days. The 
earliest observed date has been May 16 and the latest, May 31. 



13 



The full pink bud stage is still an important one in scab control 
programs. In terms of pests, the species already mentioned continue to 
develop, along with the green apple bug, Lygocoris communis (Knight), the 
apple redbug, Lygidea mendax Reut. and the pear thrips, Taenia thrips 
inoonsequens (Uzel) . 

Apple redbug and Green apple bug 

These two species of mirid bugs spend the winter as eggs hidden in the 
twigs and leading shoots of the branches. The larvae emerge at the 
full pink bud stage; the larvae of the apple redbug are bright red 
and those of the green apple bug are pale green. Current studies appear 
to indicate that these pests do more damage to apples than was previously 
believed. 

Pear thrips 

Despite its name, this insect also attacks apple, plum, cherry and peach 
trees, as well as certain forest species. The adults are black and 
measure approximately 1,5 mm in length. They burrow into the developing 
apple blossom and feed by puncturing the various organs, thus causing 
tissues to turn brown and die. In addition, the females cause other 
lesions by implanting their eggs in the petioles of the flowers and fruit 
and in the central veins of the leaves. The larvae, which are yellowish 
white in colour, drain the cellular material in the same way as the 
adults, complete their development in June and then fall to the ground for 
the pupal stage . The species is univoltine. 

FULL BLOOM 

At this stage, all the blossoms are open (PI. I, fig. 7). The average 
date of full bloom is May 23, with an accumulated total of 240 degree- 
days. The earliest observed date of flowering has been May 13 and the 
latest, June 5. 



14 



Average date: May 23 

Extreme dates: May 13 and June 5 

Degree-days: 240 

Major pests: 

European red mite 

Plum curculio 
Occasional pests: 

European apple sawfly 

Lesser apple worm 






This is the period of pollinization; a recent study on this topic assessing 
the importance of insects with respect to certain other pollinizing agents 
has been conducted in an orchard in southwestern Quebec by Miss Suzanne 
Pion and is soon to be published. 

European red mi te 

The first females and the first eggs of the European red mite appear 
during the flowering stage. The species has thus completed its first 
generation. 

Plum curculio 

The adults of this pest actually invade the apple trees during the full 
bloom period. At this time, they feed on the petals of the flowers. 

European apple sawfly 



First noted in Canada in 1940, the European apple sawfly, Hoplocampa 
testudinea (Klug), was found until recently only on Vancouver Island, in 
Bristish Columbia. However, in June 1979, this pest was observed for the 
first time in Quebec; in the spring of 1980, it was again found in a number 



15 

of orchards in the southwestern part of the Province. This insect spends 
the winter in the larval state on the ground and the adults appear on the 
apple trees at the beginning of the flowering period. They measure 
approximately 6 mm in length; their wings are transparent with prominent 
dark ribs. The abdomen and thorax are black on the dorsal portion and 
yellowish brown on the ventral portion (PI. Ill, fig. 11). 

The female lays her eggs in the flower receptable at the base of the 
sepals. The larva hatches during the fruit-setting stage and excavates 
a superficial gallery around part of the fruit. Later, the larva burrows 
to the centre of the fruit, leaving a large hole surrounded by excrement. 
The species is univoltine. 

Lesser apple worm 

Monitoring of the lesser apple worm, Grapkolttha prunivora (Walsh), by 
means of a synthetic pheromone, indicates the presence of the first adults 
in the orchards towards the end of the flowering period. 

These adults are minuscule moths, tarnished black in colour. Under the 
binocular lens, however, their forewings are rather dark brown with light 
orange brown and blue markings; they have a wingspan of approximately 
10 mm. The caterpillars, which have brown heads and pinkish white bodies, 
measure 8 mm in length at full size. They feed on the apples in the same 
way as the codling moth, Laspeyresia pomonella (L.). The damage which 
they cause is very rarely of economic importance. 

PETAL FALL 

The calyx stage is reached when 90 % of the petals of the flowers have 
fallen, which usually occurs during the last days of May (PI. I, fig. 8). 
The extreme dates for the petal fall are May 20 and June 7; the average 
date is May 29. Degree-days to this point total 300 units. 



16 



Average date: May 29 

Extreme dates : May 20 and June 7 

Degree-days: 300 

Secondary pests: 

Codling moth 

Oystershell scale 

European fruit scale 

Red-banded leafroller 



Codling moth (PI. Ill, figs. 6 and 7) 

The first adults of the codling moth are usually captured, by means of 
a synthetic pheromone, during the petal fall. At this point, degree-days 
above 11° C, calculated by the Baskerville and Emin method , total 110 
units. 

This insect is known around the world and is classified in several 
countries as a major apple pest. In Quebec, however, for the past two 
decades, it has been considered a secondary pest, having been replaced by 
the apple maggot, Rhagoletis pomonella (Walsh). Regular applications of 
insecticides to control this insect act against the codling moth as well 
and keep it below the damage level. In fact, in neglected orchards, 
codling moth populations are quite large and they do considerable damage. 

Oystershell scale 

The oystershell scale, Lepidosaphes ulmi (L.), spends the winter in the 



1 Baskerville, G.L. and P. Emin. 1969. Rapid estimation of heat 
accumulation from maximum and minimum temperatures. Ecology 50: 
514-517. 

Trottier, R. 1980. Early warning system for apple pest management in 
Canada. EPPO Bull 10: 253-257. 



17 



egg stage hidden under small comma-shaped scales attached to the bark of 
the branches. These eggs hatch during the petal fall; the new larvae are 
mobile for only a short period of time, after which they attach themselves 
somewhere on the twigs, branches or occasionally fruit to complete their 
life cycle and to cover themselves over progressively with scales. It is 
during the insect's mobile stage that treatment should occur, if required. 

European fruit scale 

With its tiny, round, slightly convex scale, the European fruit scale, 
Quadraspidiotus ostreaeformis (Curt.), can be readily distinguished from 
the oystershell scale. The species is believed to spend the winter in the 
larval stage; males and females are present in the orchards at the calyx 
stage and this is the best time for control. However, its evolutionary 
cycle has never been studied in Quebec. 

Red-banded leaf roller 

The caterpillars of this leafroller , which are pale green with straw 
yellow heads, hatch during the calyx stage. If the populations are large 
enough, this is the stage at which the first treatment should be applied. 

FRUIT SET 



Average date: June 3 

Extreme dates: May 24 - June 14 

Degree-days: 350 

Major pest: 

Plum curculio 
Occasional pest: 

Apple seed chalcid 
Natural enemy: 

Apanteles ornigis 



18 



Setting occurs approximately five days after the calyx stage; at this 
point, the apples are only about 6 mm in diameter (PI. I, fig. 9). The 
average date for setting is June 3, while the extreme dates are May 24 and 
June 14 . 

Vlvcm cuvculio 

As soon as the apples have set, the plum curculio lays its eggs on them, 
leaving a crescent-shaped scar on the fruit (PI. II, fig. 9). This pest 
lays 80 % of its eggs in June. 

Apple seed ahalaid 3 Torymus varians (Wlk. ) 

This small, bright green Hymenopteron, 3 to 4 mm long, appears at the 
setting stage and remains active for the next three weeks. The females 
lay their eggs directly in the seeds of the apples; the larva develops 
within the seed and spends the winter there. This chalcid in an 
occasional pest and the damage which it causes is often confused with 
that caused by the apple maggot. 

Apanteles ornigis (Weed) (PI. IV, fig. 10) 

This braconid plays a role of primary importance in the control of the 
leaf miner populations. In recent seasons, it has been noted that in 
orchards infested by the apple leaf miner, the rate of parasitism by 
A. ornigis was occasionally as high as 85 %. The adults of this braconid 
appear during the setting stage. 



JUNE 



19 



Tarnished plant bug 



Degree-days as of June 1: 325 

as of June 15: 510 
Major pests: 

Tarnished plant bug 

Apple maggot 

European red mite 
Secondary pests: 

Buffalo treehopper 

Codling moth 

Lesser apple worm 

Oblique-banded leafroller 

Eyespotted bud moth 

Fruit-tree leafroller 

Woolly apple aphid 

Apple redbug 

Green apple bug 
Occasional pests: 

Dogwood borer 

Rose chafer 
Natural enemies: 

Macrocentrus iridesoens 

Aphidoletes aphidimy za 

Polynema striatioorne 

Itopleotis oonquisitor 

Asaogater quadridentatus 

Amblyseius fallacis 

Anystis agilis 

Balaustium sp. 



During the first half of June, the tarnished plant bug leaves the apple 



20 
tree to confine itself to the cover crops. 

Apple maggot (PI. II, figs. 6 and 7) 

One of the most important orchard insects, the apple maggot, Bhagoletis 
pomonella (Walsh), appears at an average date of June 25 (extremes: June 
20 and July 5). At this time, the accumulated degree-days total 450 units 
above 9° C, calculated according to the Baskerville-Emin formula cited 
above. For a number of years, the apple maggot has been subject to 
monitoring in Quebec. 

European red mite 

Most of the individuals appearing during the month of June are members of 
the 2nd and 3rd generations. 

Buffalo treehopper 

The hibernating eggs of the buffalo treehopper hatch during the first half 
of June. The nymphs and adults feed on herbaceous plant, preferably 
leguminous plants. 

Codling moth and Lesser apple worm 

Large numbers of these two species are still being captured by means of 
synthetic pheromones during the entire month of June. The eggs of the 
codling moth hatch about mid-June, when accumulated degree-days total 210 
units above 11° C, as calculated by the Baskerville-Emin formula. 

Oblique-banded leaf roller 

Catches of oblique-banded leaf roller moths begin between June 10 and 15, 
and reach their peak at the end of June and the beginning of July. 



21 

Eyespotted bud moth and Fruit- tree leafroller 

As with the previous species, the adults of these two pests are 
particularly numerous at the end of June and the beginning of July. 

Woolly apple aphid 

In mid- June, the woolly apple aphid, Eriosoma lanigerum (Hausm.), can 
already be found, particularly on incompletely healed wounds caused by the 
pruning of the apple trees. 

Apple vedbug and Green apple bug 

The adults of these two univoltine species appear in June (PI. II, figs. 
4 and 5) . 

Dogwood borer 

The adults of the dogwood borer, Thamno sphecia scitula (Harr.), with its 
black body, yellow markings and transparent wings, are active from the 
end of June to mid-July. The caterpillar of this species is whitish and 
feeds on sap, remaining in tunnels under the bark of apple trees which 
are already weak and lacking in vigour. Reddish wormholes on the bark 
reveal its presence. Since 1979, tests aimed at monitoring this species 
have been carried out. 

Rose chafer 

Towards mid-June, the adults of the rose chafer, Macrodactylus subspinosus 
(F.), occasionally attack certain orchards planted near very sandy areas. 
These beetles, approximately 9 mm long, are yellowish brown in colour, 
have long legs, and chew holes of varying depths in the fruit. 



22 
Maovocentous iridesoens French (PI. IV, fig. 6) 

In an experimental orchard which received no insecticide treatment, this 
polyembryonic bracomid has, in the last two seasons, practically eliminated 
the hibernating caterpillars and first-generation caterpillars of the 
oblique-banded leafroller . This species merits special attention. 

Aphidoletes aphidimy m (Rondani) (PI. IV, fig. 7) 

This cecidomyid, which is a major predator of the apple aphid, the rosy 
apple aphid and the woolly apple aphid, appears at the beginning of June. 

Polynema striaticorne Gir. 

This is a chalcid, the adults of which appear during the first half of 
June and which is an important parasite of buffalo treehopper eggs. 

Iiopleotis conquisitor (Say) (PI. IV, fig. 8) 

This endoparasite is very common and attacks a number of insects, 
particularly the leafrollers and the apple bud moth. 

Ascogaster quadridentatus (Wes.) (PI. IV, fig. 11) 

This braconid, approximately 4 mm long, attacks the eggs of the codling 
moth and develops within the larva. The adult appears in mid-June as 
the first codling moth larvae are hatching. In commercial orchards, the 
rage of parasitism is approximately 6 %, but may go as high as 25 %. 



Amblyseius fallacis (Gar.) (PI. IV, fig. 12), Anystis agilis Banks and 
Balaustium sp. 



The predators of the European red mite are extremely numerous, but 
disappear from commercial orchards as a result of insecticide treatments. 



23 



A. fallacis, A. agilis and Balaustium sp. are the only species found in 
small numbers in commercial orchards after mid-June. 

In 1979, there was a first attempt to introduce specimens of Amblyseius 
fallaois which were resistant to certain organophosphate insecticides. 
The results obtained have been extremely encouraging. 



JULY 



Apple maggot 



Degree-days as of July 1: 
as of July 15 

Major pests: 
Apple maggot 
European red mite 
Plum curculio 

Secondary pests: 

Red-banded leafroller 
Eyespotted bud moth 
Apple aphid 

Natural enemies: 

Trioho gramma minuturn 
Agathis latioinctus 
Diadegma obi i tera tus 
Sarcophaga aldrichi 



725 
950 



The period of maximum activity for this insect occurs from mid-July to 
mid-August . 



24 

European red mite 

In July, most of the individuals are members of the 3rd and 4th generations; 
populations normally reach their highest density by the end of July and 
the beginning of August. 

Plum curculio 

Towards mid-July, the larvae of this curculio leave the apples and burrow 
into the ground where they will spend the pupal and adult stages; the 
adults appear primarily during the 3rd week of August. The presence of new 
adults is revealed primarily by an increase in the number of feeding 
punctures (PI. II, fig. 10). 

Red-banded leaf roller 

The beginning of July marks the first catches of adults of this leaf 
roller, which will give birth to the second generation. 

Eyespotted bud moth 

Large numbers of caterpillars of the new generation, which will become 
the hibernating caterpillars, appear around July 20. 

Apple aphid 

By late July, there is usually a sharp decline in the populations of 
apple aphids, which may be due to climate conditions and the leathery 
condition of the foliage. 

Triohogramma minutum Riley 

In Quebec's apple orchards, this cosmopolitan parasite has often been 
observed in July emerging from the eggs of the r ed-banded leaf roller and 






25 



the apple budmoth, among others. 

Agaihis laticinotus (Cress.) (PI. IV, fig. 4) 

This braconid is a major parasite of the eyespotted budmoth, and may reduce 
larval populations by as much as 50 %. The adults appear about mid-July. 

Diadegma oblitevatus (Cress.) (PI. IV, fig. 5) 

This parasite attacks leaf rollers, olethreutids and leaf miners. 

Saraophaga aldriohi Park. (PI. IV, fig. 9) 



This tachinid attacks the cocoons of the forest tent caterpillar in 
particular, and can decimate this species in neglected orchards. 

AUGUST 



Degree-days as of August 1: 1200 

as of August 15: 1450 
Major pest: 

European red mite 
Secondary pests: 

Codling moth 

Lesser apple worm 

Buffalo treehopper 

Red-banded leaf roller 
Woolly apple aphid 
Apple rust mite 



26 



European red mite 

This mite completes its 4th and 5th generations and, during the month of 
August, the first hibernating eggs can be found on the bark of the branches 
or in the eyes of the apples. 

Codling moth and Lesser apple worm 

At the beginning of August, the moths of these two pests, which will give 
birth to a partial second generation, appear. 

Buffalo treehopper 

Also at the beginning of August, the females of the buffalo treehopper 
leave the herbaceous plants and invade young apple trees. Besides laying 
their eggs deep in the inner bark of the trunks and twigs, they make two 
slits in the bark near each group of eggs. When there are many of 
these slits, they can interfere with the growth of the young trees. 

Red-banded leafroller 

Nearly all the caterpillars of the second generation of this leafroller 
have hatched by the beginning of the month of August. 

Woolly apple aphid 

It is also at the beginning of August that we observe heavy infestations 
of the woolly apple aphid, which, in recent years, have become more 
widespread. 

Apple rust mite 

It is during the month of August that the first deutogynous females 
appear, those that will spend the winter beneath the scales of the buds 









27 



or in the folds of the bark. 

II - MONITORING AND CONTROL 

Under current conditions, it is difficult to visualize commercial apple 
production without the use of a certain number of insecticide treatments. 
For this reason, we propose basic treatments which are suitable for most 
orchards and directed against the major pests, which at the present time 
are the European red mite, the apple maggot, the phytophagous plant bugs, 
the plum curculio and the green fruitworm. Where necessary, we also 
recommend additional or special treatments for local and seasonal problems, 

The basic treatments include a preliminary application of insecticide at 
the pink bud stage, directed against the tarnished plant bug and the 
green fruitworm. This treatment may also have a repressive effect on 
secondary or occasional pests present at this time, such as the tent 
caterpillars, the oblique-banded leaf roller , the fruit-tree leafroller , 
the leafminers , the bud moth and the aphids (Table 1) . 

A second treatment, recommended at the calyx stage, is directed against 
the plum curculio and against the plant bugs; it may also be effective 
against the scales, the red-banded leafroller , the European apple sawfly, 
the gypsy moth and, again, against the aphids. 

A third treatment is carried out against the European red mite and is 
applied when an average of five mobile forms of this mite can be found 
on each leaf. In some cases, it can be combined with the previous or 
subsequent application. This treatment also eliminates the populations of 
the apple rust mite and the two-spotted spider mite. 

A fourth and fifth basic treatment are performed towards July 10 and July 
25 respectively against the apple maggot; these treatments may also be 
effective against the apple worms, the aphids, the leaf rollers and the 
eyespotted bud moth. 



28 



TABLE 1 Basic treatments directed against major pests in relation to 
secondary or occasional pests which may be present. 



Time of 
treatment 



Major 
pests 



Secondary of 
occasional pests 



Pink bud 



Calyx 



June 


or 


July 




July 


10 


July 


25 



tarnished plant bug 
green fruitworm 



plum curculio and 
phytophagous plant 
bugs 

european red mite 



apple maggot 



apple maggot 



tent caterpillars, oblique- 
banded leaf rollers, fruit- 
tree leaf roller, leaf 
miners, bud moth, aphids 

scales, red-banded leaf 
roller, aphids, sawfly, 
gypsy moth 

apple rust mite, two-spotted 
spider mite 

codling moth, aphids, 
leaf rollers, bud moth 

codling moth, aphids, 
leaf rollers, bud moth 



With additional or special treatments, certain precautions must be taken, 
since, for example, the leaf miner populations to be eliminated may be 
heavily infested with parasites or the aphid colonies involved may include 
numerous predators. In these cases, applications of insecticides are not 
only useless, but harmful. This is when a knowledge of the principal 
parasites and predators normally present in orchards becomes very important 
to both the agricultural adviser and the fruit grower himself. 



A monitoring program can also prove very useful in determining the presence 

of a given pest, the density of the population and the need for treatment. 

Two types of traps are currently being used with success in certain 

orchards in Quebec: 

. the synthetic sexual pheromone trap, and 

. the bait trap, based primarily on colour attraction. 

The pests currently subject to monitoring can be divided as follows: 



29 



Pheromone traps 



Bait traps 



Red-banded leafroller (1) 
Codling moth (1) 
Oblique-banded leafroller (1) 
Fruit-tree leafroller (1) 
Lesser apple worm (1) 
Dogwood borer (2) 
Leaf miner (2) 
Green fruitworm (3) 



Apple maggot (1) 
Tarnished plant bug (4) 
Apple sawfly (4) 



The pheromone trap holds a capsule impregnated with a synthetic substance 
similar to that given off by the female of a given species. This capsule 
is placed in a flared, pre-glued cardboard trap; it can be effective over 
an area of approximately two hectares for a month. 

The bait trap for the apple maggot is made of pre-glued yellow cardboard 
(14 x 23 cm) with an ammoniac-based bait. It should be placed in the 
areas most subject to attacks by this maggot. The bait trap for the 
tarnished plant bug and the european apple sawfly is made of cardboard 

(15 x 20 cm) covered with white zinc pigments which do not reflect 

(R) 
ultraviolet radiation and with a glue known as Tangletrap 

For the red-banded leafroller , the codling moth, the oblique-banded leaf 
roller and the apple maggot, mentioned in the table below, we are in a 
position to give the dates for trap installation, the monitoring periods 
and the critical number of catches at the end of the monitoring period: 



(1) Zoe'con Corporation, Palo Alto, California 94304. 

(2) Conrel, Needham Heights, Massachusetts 02194. 

(3) Prairie Regional Laboratory, NRC Canada, Saskatoon, Sask S7N 0W9 . 

(4) New England Insect Traps, Colrain, Massachusetts 01340. 



30 



Insect 



Date of trap 
installation 



Trapping 
period 



Critical number 
of total catches 



Red-banded leafroller 

Codling moth 

Oblique-banded leaf- 
roller 

Fruit-tree leafroller 

Red-banded leafroller 
(2nd generation) 

Apple maggot 

Oblique-banded leaf- 
roller (2nd generation) 



April 15 


April 20 - May 20 


600 


May 15 


May 20 - June 20 


20 


May 25 


June 1 - July 1 


100 


June 15 


June 20 - July 20 


20 


June 20 


June 25 - July 25 


200 


June 20 


June 25 - September 1 


1 


August 1 


August 5 - September 5 


100 



1 Sum of catches in 2 traps per orchard, except for the apple maggot, with 
4 traps per orchard. The critical numbers of catches may be modified 
following further information. 



The critical thresholds which we suggest are provisional and, for proper 
use of these monitoring techniques, the inexperienced fruit grower should 
consult an agricultural adviser. For species not listed in the table, 
research is continuing in an effort to establish the relationship between 
catches and damage with all possible accuracy. 



This brief survey of the area of apple orchard protection against pests 
is, of necessity, incomplete; it may help, however, to demonstrate the 
complexity of the problems and the efforts which have been made to 
develop a rational, rather than preventive and empirical, policy of control, 



31 

Acknowledgements 

Messrs. A. Clement, D. Pitre and L.G. Simard of Agriculture Canada and 
Mr. J. Touzin of the Quebec Department of Agriculture, Fish and Food have 
made an important contribution as technicians to the basic work of this 
research. In addition, with the assistance of Mr. B. Drouin, a graphic 
artist with the Quebec Department of Agriculture, Fisheries and Food, they 
have prepared the colour plates illustrating this report. 



32 



PLATE I - Phonological stages in the development of Mcintosh apple trees 

1. Dormant 

2. Green tip 

3. Half-inch green 

4. Tight cluster 

5. Pink 

6. Advanced pink 

7. Full bloom 

8. Petal fall 

9. Fruit set 

Pho ivs: 

L.G. Simard 



36 
PLATE II - Major apple pests 

1. Female European red mite, Panonychus ulmi (Koch); length 0,39 mm. 

2. Specimens of the apple rust mite, Aoulus schleohtendali (Nal.); 
length 0,07 mm. 

3. Tarnished plant bug, Lygus lineolaris (P. de B.); length 5,6 mm. 

A. Apple redbug, Lygidea mendax Reut ; length 6,6 mm. 

5. Green apple bug, Lygocoriu communis (Knight); length 5,6 mm. 

6. Apples attacked by the apple maggot, Rhagoletis pomonella (Walsh). 

7. Male apple maggot; body length 5 mm. 

8. Adult plum curculio, Cono tracheitis nenuphar (Hbst.); length 5 mm. 

9. Egg punctures of the plum curculio on newly set apples. 

10. Feeding punctures of the plum curculio. 

11. Caterpillar of the green fruitworm, Orthosia hibisci (Guenee) . 

12. Adult green fruitworm; wingspan A0 mm. 

13. Scar on ripe apple caused by the caterpillar of the green fruitworm, 

Pho tos: 

L.G. Simard, No. 1, 2, 3, A, 6, 7, 8, 10, 11, 13 

B. Drouin, No. 5, 9 





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40 
PLATE III - Secondary apple pests 

1. Wingless forms of the apple aphid, Aphis pomi De G. 

2. Wingless forms of the rosy apple aphid, Dysaphis plantaginea (Pass.)- 

3. Colonies of the rosy apple aphid on a leading shoot. 

A. Adult oblique-banded leaf roller, Archips rosaceana (Harr.); 
length 11,5 mm. 

5. Apples attacked by the caterpillar of the oblique-banded leaf roller. 

6. Adult codling moth, Laspeyresia pomonella (L.); lenght 10 mm. 

7. External appearance of a fruit containing the larva of the codling moth, 

8. Adult and pupa of the eye-spotted bud moth, Spilonota ocellana 
(D. & S.); length of adult 7,5 mm. 

9. Adult and nymphal cuticle of the fruit-tree leaf roller, Avchipa 
argyrospilus (Wlk.); length of adult 10,6 mm. 

10. Scars caused by caterpillars of the fruit-tree leaf roller on mature 
apples . 

11. Adult european apple sawfly, Hoplooampa testudinea (Klug); length 
6 mm. 

Photos: 

E. Drouin, No. 1, 2, 3, 8, 11 

L.G. Simard, No. 4, 5, 6, 7, 9, 10 



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44 
PLATE IV - Some natural enemies of apple pests 

1. Alio thrombium lerouxii Moss; length 3,3 mm. 

2. Syrphid egg; length 1 mm. 

3. Syrphid larva. 

3a. Predatory ladybirds 

4. Agathis latioinctus (Cresson); length 4,2 mm. 

5. Diadegma obliteratus (Cresson); length 4,5 mm. 

6. Macrocentrus iridesaens French; length 3,2 mm. 

7. Aphidoletes aphidimyza (Rondani); length 1,8 mm. 

8. Itoplectis aonquisitor (Say); length 8,2 mm. 

9. Sarcophaga aldrichi (Park.); length 4,3 mm. 

10. Apanteles ornigis (Weed); length 2,3 mm. 

11. Ascogaster quadriden ta tus Wes.; length 4,3 mm. 

12. A colony of Amblyseiue fallacis (Garman) ; length of adult 0,32 mm. 

Photos: 

B. Drouin, No. 1 

J. Touzin, No. 2, 3, 3a 

L.G. Simard, No. 4, 5, 6, 7, 8, 9, 10, 11, 12 



IV 




47 



INDEX 



Page Page 

Aoulus sahleahtendali see apple rust bait traps 28, 29 

mite Bataustivm sp 19 , 22 

Agathis latioinatus buffalo treehopper 19, 20, 25, 26 

23, 25; PI. IV, fig. 4 click beetles 5, 7 

Allothrombium lerouxii codling moth 16, 19, 20, 22, 25 

3, 4; PI. 4, fig.l 26, 28, 29, 30; PI. Ill, figs. 6 and 7 

Amblyseius fallaais Conotraohelus nenuphar see plum 

19, 22; PI. IV, fig. 12 curculio 

Anystis agilis 19, 22 Ctenieeva spp. see click beetles 

Apanteles ovginis degree-days 2, 3, 5, 8, 10, 11 

17, 18; PI. IV, fig. 10 12, 13, 14, 15, 16, 17, 19, 23, 25 

Aphidoletes aphidimyza Diadegma oblitevatus 

19, 22, PI. IV, fig. 6 23, 25; PI. IV, fig. 5 

Aphis pomi see apple aphid dogwood borer 19, 21, 29 

apple aphid Dysaphis plantaginea see rosy apple 

10, 23, 24, 28; PI. Ill, fig.l aphid 

apple grain aphid 5, 6 Eastern tent caterpillar 5, 7 

tentiform leafminer 8, 9, 29 Eriosoma lanigerum see woolly apple 

apple maggot... 1, 16, 19, 20, 23, 27 aphid 

28, 29, 30; PI. II, figs. 6 and 7 European apple sawfly 

apple red bug 14, 28, 29; PI. Ill, fig. 11 

12, 13, 19, 21; PI. II, fig. 4 European fruit scale 16, 17 

apple rust mite European red mite 1, 11, 14, 19, 20 

5, 25, 26, 28; PI. II, fig. 2 23, 24, 25, 26, 27, 28; PI. II, fig.l 

apple scab 4 eye-spotted bud moth 5, 6, 19 

apple seed chalcid 17, 18 21, 23, 24, 25, 27, 28;P1.III, fig. 8 

Avohips argyrospilus see fruit-tree forest tent caterpillar 5, 7 

leafroller fruit-tree leaf roller 

Avohips rosaaeana see oblique- 11, 12, 19, 21, 27 

banded leafroller 28, 29, 30; PI. Ill, figs. 9 and 10 

Avgyvotaenia velutinana see red- fruit set 17; PI. I, fig. 9 

banded leafroller full bloom 13; PI. I, fig. 6 

Asaogaster quadridentatus full pink 12; PI. I, fig. 6 

19, 22; PloIV, fig. 11 Grapholita pvunivora see lesser apple- 
worm. 



48 

Page Page 
green apple bug oblique-banded leaf roller 

12, 13, 19, 21; PI. II, fig. 5 5, 6, 19, 20, 22 

green fruitworm 1, 3, 10, 27 27, 28, 29, 30; PI. Ill, figs. 4 and 5 

28, 29; PI. II, figs. 11, 12 and 13 Orthosia hibisci see green fruitworm... 

green tip 4; PI. I, fig. 2 oystershell scale 16, 17 

gypsy moth 8, 9 pale apple leaf roller 3, 4 

half -inch green 7; PI. I, fig. 3 Panonychus ulmi see European red mite.. 

Hoplocampa testudinea see European pear thrips 12, 13 

apple sawfly pests, major.... 1, 2, 3, 10, 11, 14, 17 

Itoplectis oonquisitov 19, 23, 25, 27, 28; PI. II, figs. 1-13 

19, 22; PI. IV, fig. 8 pests, occasional 

lady beetles 5, 7; PI. IV, fig. 3a ..2, 3, 5, 8, 12, 14, 17, 19, 27, 28 

Laspeyresia pomonella see codling pests, secondary. 2, 5, 8, 10, 11, 12, 16 

moth 19, 23, 25, 27, 28; PI. Ill, figs. 1-11 

Lepidosaphes ulmi see oystershell petal fall 15; PI. I, fig. 8 

scale pheromone traps 28, 29 

lesser appleworm pink bud 10; PI. I, fig. 5 

14, 15, 19, 20, 25, 26, 27, 29 plant bugs 1, 27, 28 

Lithocolletis blancavdella see plum curculio 1, 11, 14, 17, 18, 23 

tentiform leafminer 24, 27, 28; PI. II, figs. 8, 9 and 10 

Lithocolletis cavtaegella 9 Polynema stviaticovne 19, 22 

Lithocolletis malimalifoliella 9 Pseudexenteva mali see pale apple 

Lithocolletis scudevella 9 leaf roller 

Lygidea mendax see apple red bug Quadraspidiotus ostreaeformis see 

Lygocovis communis see green apple European fruit scale 

bug red-banded leaf roller. 

Lygus lineolaris see tarnished plant 5, 6, 25, 26, 27, 28, 29, 30 

bug rose chafer 19, 21 

Lymantvia dispar see gypsy moth Rhagoletis pomonella see apple maggot.. 

Macvocentrus ividescens Rhopalosiphum fitchii see apple grain 

19, 22; PI. IV, fig. 6 aphid 

Macrodactylus subspinosus see rose rosy apple aphid 

chafer 8, 9; PI. Ill, figs. 2 and 3 

Malacosoma americanum see Eastern Sarcophaga aldnihi. 23, 25; PI. IV, fig. 9 

tent caterpillar Spilonota ocellana see eye-spotted bud 

Malacosoma disstria see forest tent moth 

caterpillar spring dormancy 3; PI. I, fig.l 



49 



Page Page 

syrphid flies Thamosphecia scitula see dogwood 

5, 7, PI. IV, figs. 2 and 3 borer 

Taeniothrips inaonsequens see pear tight cluster 9; PI. I, fig. A 

thrips. Tovymus varians see apple seed 

tarnished plant bug chalcid 

3 5 19 27 28 29* PI. II fig. 3 Triehogramma minutum 23, 24 

Tetranychus urticae see two-spotted two-spotted spider mite 8 

'der mite Venturia inaequalis see apple scab... 

woolly apple aphid 20, 21, 27, 28 



LIBRARY / BI8LI0THEQUE 

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AGRICULTURE CANADA OTTAWA K1A OC5 

3 =1073 00012503 5 



630.72 

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Paradis, Rodolphe-O. 

Pest management approach in 
Quebec apple orchards